A synopsis of a frame creak on my Stumpy FSR Evo29 carbon

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A synopsis of a frame creak on my Stumpy FSR Evo29 carbon
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flag pj726e
Posted: May 11, 2015 at 21:21 Quote
I've developed a resonating, low pitched, bad frame creak on my 2013 model stumpy FSR evo . It will only happen in the middle of a ride, after a series of high speed (not mph, shock action speed) rocks and hits. Like I said it is a low pitched sound that negatively affects the rear suspension's action considerably. It feels as though there is a bind within the suspension linkage. However, as soon as I start to ride smooth sections of the trail, the sound and its negative effects tends to go away. It can go away and come back in a ride, dependent upon the trail conditions.

Heres what I know:
- I bought the bike second hand, its in good shape. The first time two times I rode it, no creak, but the trails were pretty flat.
- I adjusted the command post AFTER the 2nd ride and torqued the seat binder back to spec (44in/lbs). I cleaned and lubed the tube with a light coat of belray waterproof grease. During the rides I would adjust the tension on the seat tube binder, which made no difference.
- Creak sounds when sitting in the saddle AND standing up out of the saddle.
- I've cleaned and inspected every bearing in the frame. All in good shape, no reason for any fault here.


- Heres where I'm mostly curious. The metal upper shock bushing (FOX ctd w/ autosag & kashima) appears to be seized. Could this be where the creak is coming from ? I've read Fox sells an improved polymer shock bushing to replace the metal unit. Does anyone know what size bushings to use in the FSR EVO 29 FOX CTD?

I'm at my wits end with the issue. I've been on a half dozen rides with the creak and aside from the annoying noise, the rear suspension when it creaks feels like it is suffering from stiction and a bind. It does not ride well like this, I actually feel bad riding it this way.

Does anyone have any recommendations or advice?
flag TheRaven
Posted: May 19, 2015 at 8:14 Quote
pj726e wrote:
- Heres where I'm mostly curious. The metal upper shock bushing (FOX ctd w/ autosag & kashima) appears to be seized. Could this be where the creak is coming from ? I've read Fox sells an improved polymer shock bushing to replace the metal unit. Does anyone know what size bushings to use in the FSR EVO 29 FOX CTD?

If the suspension seems to be binding when you hear the creak, then i'd venture to guess that it could actually be the shock hardware. Those metal DU bushings are often overlooked when a frame is overhauled. Pretty much every frame i've ever bought secondhand has come with bad DU bushings.

The Fox polymer (IGUS) bushings are excellent. Certainly better than metal DU, and IMO better than needle-bearings as they don't have a reputation of developing play like the needle bearings do. That's why one of the first things I do when restoring an old frame that I bought used is order the correct polymer bushings for the shock.

Just remove your shock, and precisely measure the distance between the bolt eyes on the frame's shock mount. It has to be PRECISE because the bushing spacers are made in fractions of a MM. So for instance, you could measure 22mm, and then go to order and find that you have two choices - 21.78mm and 22.13mm. One of those could bind, or have excess play. So make you measure and re-measure carefully. I believe your frame has the lower clevis-mount, so i'm not sure if there's a DU bushing there or not, and as such, dunno how you would measure for it. I have yet to rehab one of those designs.
flag pj726e
Posted: May 20, 2015 at 18:56 Quote
TheRaven wrote:
pj726e wrote:
- Heres where I'm mostly curious. The metal upper shock bushing (FOX ctd w/ autosag & kashima) appears to be seized. Could this be where the creak is coming from ? I've read Fox sells an improved polymer shock bushing to replace the metal unit. Does anyone know what size bushings to use in the FSR EVO 29 FOX CTD?

If the suspension seems to be binding when you hear the creak, then i'd venture to guess that it could actually be the shock hardware. Those metal DU bushings are often overlooked when a frame is overhauled. Pretty much every frame i've ever bought secondhand has come with bad DU bushings.

The Fox polymer (IGUS) bushings are excellent. Certainly better than metal DU, and IMO better than needle-bearings as they don't have a reputation of developing play like the needle bearings do. That's why one of the first things I do when restoring an old frame that I bought used is order the correct polymer bushings for the shock.

Just remove your shock, and precisely measure the distance between the bolt eyes on the frame's shock mount. It has to be PRECISE because the bushing spacers are made in fractions of a MM. So for instance, you could measure 22mm, and then go to order and find that you have two choices - 21.78mm and 22.13mm. One of those could bind, or have excess play. So make you measure and re-measure carefully. I believe your frame has the lower clevis-mount, so i'm not sure if there's a DU bushing there or not, and as such, dunno how you would measure for it. I have yet to rehab one of those designs.

Thankyou. Gonna get a nice digital caliper and measure the width and replace with the IGUS bushing. Any special tool for the installation of the polymer bushing?
flag TheRaven
Posted: May 21, 2015 at 5:30 Quote
Nope...the polymer bushings can be installed by hand, though a pair of standard (or channel-lock) pliers would be handy to have on hand as assembling the spacer can sometimes require a little extra force. I've always been able to do it by hand though.

You WILL need to press out the old DU bushing, of course. Using a bench vise with the tried-and-true socket method is preferable, or you could assemble your own press using the bolt/nut/washers method. There is tons of info out there on this process so a simple google search will yield a step by step if you need it.

Another point of note - I had an Epic that would continually develop creak over time at the upper shock mount (the shock mounted using the same bolt as the horst-link). All I had to do was disassemble that mount, and clean and grease the crap out of everything, then re-assemble. However, the creak would always return after a few months of riding. So this became routine maintenance. The first time I found it I had to sit on the bike and bounce while a friend just put his ear up to each pivot-point until he found where the noise was coming from. You may want to try that before you start buying parts.
flag pj726e
Posted: May 21, 2015 at 14:42 Quote
I've pressed out the old bushing with a couple of appropriate sized sockets already. The DU bushing appeared to be in good shape. Regardless I've heard the IGUS bushing is a good cheap upgrade from the metal unit. Still working on getting a set of nice calipers to accurately measure the gap of the spacer before ordering parts. The stumpy FSR does not use a lower shock bushing, it has a fork at the bottom which links to two sealed bearings.

Cleaning and applying a light coat of grease was my first step, on EVERY pivot. I can cross that off the list. After that I torqued everything to spec according to the 2014 Specialized manual. This frame is a 2013 but from my knowledge, its the same.

The problem with checking for noises, is that the frame only creeks when I'm riding the bike, after 20 minutes or so of rocky, rooty trails. I can't diagnose the problem in the driveway or on the stand. It's difficult to get an ear up to it while it's creaking.

Really appreciate the help again. I'll let you know what happens after I install the IGUS bushing.
flag pj726e
Posted: May 28, 2015 at 19:09 Quote
Installed new DU bushing correctly and went for a ride. The creek is still there. The sound is still coming from the shock. Could it be the shock itself ?
flag TheRaven
Posted: May 29, 2015 at 6:47 Quote
pj726e wrote:
Installed new DU bushing correctly and went for a ride. The creek is still there. The sound is still coming from the shock. Could it be the shock itself ?

Highly unlikely. I can't think of anything on a shock that could create a "creak" type of sound. I've also never heard of that happening. Ever.

Are you absolutely sure it's the shock? Creaks can be deceiving. When I finished my new Tracer build I had a really bad creak that I was sure was coming from the crankset. I took it all apart and cleaned and re-lubed and re-assembled and re-torqued, and the creak was then quieter, but still present...however this time it sounded like it was coming from the saddle. So I re-tightened the bolts that secure the seat rails and that helped but the creak was still audible. So I re-tightened the bolts that hold the top part of the saddle to the bottom, and that helped alot. But there was still a very slight creak audible when the crankset was at the 12 and 6 o'clock positions, so I once again rehabbed the crankset. That didn't get rid of it. At that point, I stopped caring.
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